Area Forecast Discussion
Issued by NWS Central Illinois

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000
FXUS63 KILX 191734
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1234 PM CDT Sun Oct 19 2014

.UPDATE...
ISSUED AT 956 AM CDT SUN OCT 19 2014

Persistent area of clouds that failed to completely clear out of
central Illinois last night remains in place across parts of the
area this morning. 1430z visible satellite imagery shows cloud
cover along/east of a Peoria to Springfield line. These low clouds
are beginning to advance to the E/NE as S/SW winds develop on the
back-side of departing high pressure. As winds increase, the
forward speed of the clouds will as well, so am expecting them to
depart the CWA into Indiana by early afternoon. After that, mostly
sunny skies with only a few high/thin cirrus clouds can be
anticipated for the balance of the day. Due to the sunshine and
southwesterly winds, afternoon high temperatures will be quite a
bit warmer than previous days, with readings reaching the upper
50s and lower 60s. Made some adjustments to hourly sky grids to
better time the expected clearing and tweaked hourly temps.
Forecast update has already been issued.

&&

.SHORT TERM...(Today)
ISSUED AT 305 AM CDT SUN OCT 19 2014

Pesky low clouds continue to linger across the southern 2/3 or so of
the forecast area early this morning. This fact is holding surface
temperatures and dew points up considerably, and mitigating the
frost threat. However, temperatures have fallen to frosty level
across northern portion of the forecast area where skies have
cleared. HRRR and RAP models both suggest clouds should linger for
at least a few more hours across much of the southern CWA, something
that is hard to argue with looking at recent satellite trends. So,
plan to drop Frost Advisory from the southern half of the forecast
area.

Otherwise, quiet weather is on tap for the forecast area today, with
weak short wave ridging drifting overhead, and the associated
surface ridge pushing off to the east. Low level return flow on the
back side of the surface ridge will help push temperatures back into
the 60s today across much of the forecast area. However, the tricky
cloud cover forecast would likely impact how warm we ultimately get.
While most of the synoptic models suggest a mostly sunny day can be
expected, the high resolution HRRR & RAP, suggest at least the first
half of the day may trend closer to mostly cloudy. The high res
models have a better handle on what is occurring at the moment, so
I`m reluctant to disregard their solutions.

&&

.LONG TERM...(Tonight through Saturday)
ISSUED AT 305 AM CDT SUN OCT 19 2014

A fast moving wave currently across North Dakota is expected to drop
into the Great Lakes on Monday. The main low will stay well to our
northeast, with the trailing cold front sweeping through the
forecast area through early Monday afternoon. The threat of showers
with this feature is mainly across the southeast half of the
forecast area late evening through the overnight hours, with the GFS
and ECMWF both in decent agreement, while the NAM persists with a
dry forecast. Soundings do not show much moisture, so any showers
that occur will be fairly light. Have lingered some 30% PoP`s in the
far southeast CWA into early Monday morning, although have limited
this to areas south of I-70.

Otherwise, largely quiet week on tap for the area, as skinny ridge
builds toward the Mississippi Valley mid week with development of a
large cutoff low over the eastern states. As the eastern low slowly
drifts east late week, a deep shortwave across the Plains will
eventually split with a piece of energy forming a secondary cutoff
low over the lower Mississippi Valley. As this occurs, the threat of
rain east of the river will evaporate quickly Thursday evening with
the moisture being drawn toward this southern low.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
ISSUED AT 1234 PM CDT SUN OCT 19 2014

MVFR ceilings persist at the central Illinois terminals early this
afternoon as low-level moisture remains trapped below a strong
subsidence inversion. Moisture has been very slowly shifting
eastward over the past couple of hours, and latest HRRR continues
this trend through the afternoon. Based on satellite timing tools,
will scatter the ceilings at KSPI by 19z, then further east to KCMI
by around 21z. Once low clouds clear out, quite a bit of high
cirrus clouds will stream across the area this afternoon/evening
in advance of a trough axis currently extending from Minnesota to
Nebraska. Latest satellite and regional obs indicate only mid/high
clouds associated with this boundary: however, as it drops
southeastward later tonight into Monday morning, most models are
showing a marked increase in 1000-850mb RH. Soundings remain
rather dry, so am expecting little more than a few sprinkles early
Monday morning. However, have included low VFR ceilings at all
sites except KPIA and KSPI as the boundary passes. After that,
winds will veer to the W/NW and skies will clear toward midday.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...Barnes
SHORT TERM...Bak
LONG TERM...Geelhart
AVIATION...Barnes






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